JP4801511B2 - Ball screw - Google Patents

Description

  In particular, the present invention relates to a ball screw that circulates balls using ball circulation pieces called deflectors on both ends of a nut.

  Conventionally referred to as a deflector system, a ball (steel ball) is scooped up from the spiral thread groove space between the inner surface of the nut and the outer surface of the screw shaft using a piece, through one side of the nut, and opposite the nut through the return passage inside the nut Various types of ball screws have been proposed and put into practical use as a method of returning to the thread groove space from the side and performing a continuous circulation motion.

  For example, an end deflector type ball screw as disclosed in Patent Document 1 is known. The piece that is a circulating part in such a deflector system has a circulation passage that communicates the return passage of the nut and the thread groove space, and is manufactured by a precision casting product such as an integral molded product such as lost wax, Or it is manufactured with the injection molding article by a synthetic resin.

  Certainly, the manufacturing accuracy of these products has improved, and the connection between the passages during assembly has been greatly improved, but the product manufacturing error is not only the piece itself, but also the mounting nut. It is also in the notch, and the assembly adjustment of each ball screw product is very large in product performance and has an important meaning. In other words, depending on how smoothly these connecting portions are connected, the circulating ball will pass through reasonably and affect the generation of vibration and noise.

Japanese Examined Patent Publication No. 1-27303

  In the above-described prior art, if the connecting portion of the communicating portion to the return passage on the nut side of the piece is matched at the time of assembly, further fine adjustment is required in the connecting portion of the scooping portion from the other thread groove space. In addition, since the connecting part of such a piece is usually not visible, the part is assembled and passed through the ball, and the assembly worker judges the sound and vibration at that time with his / her ears and fingertips, and the part is scooped up manually. It is necessary to rework and assemble, and it takes assembling man-hours. In addition, performance tends to vary from product to product and from worker to worker, and it is difficult to maintain the uniformity of the quality of the entire product.

  Furthermore, various types of structures such as those described in Patent Documents 2 and 3 have recently been proposed for such a deflector-type ball screw. In these devices, a device using a ball guide member having a support protrusion or a supporting shoulder is shown. Both of these two similar structures constitute a ball rolling passage between the surface of the nut notch and the surface of the piece, and accurately form the positional relationship to the nut notch to which the ball guide member is attached. Therefore, the shape of the notch of the nut becomes complicated.

  In other words, the ball guide member is to be attached to the nut by aligning the notch to the nut with the above-described support protrusion or the supporting shoulder, and it is difficult to make fine adjustments after the attachment. Become.

Registered Utility Model No. 3034052 JP 2003-294103 A

  The object of the present invention is to solve the above-mentioned problems, achieve a low noise at a high peripheral speed, smoothly scoop up from the screw rolling groove to the circulating piece on the nut side, and from the circulating piece to the return passage of the nut. It is an object of the present invention to provide a ball screw that achieves smooth rolling and allows fine adjustment of the connecting portion of the ball scooping portion to the circulation piece.

In order to achieve the above object, a ball screw according to the present invention includes a screw shaft having a screw groove formed on an outer peripheral surface thereof, a screw groove screwed into the screw groove formed on an inner peripheral surface, and a side surface penetrating in an axial direction. A nut having a ball return passage, a ball circulation piece having a curved ball circulation passage communicating between the both screw grooves and the ball return passage, and mounted on both side surfaces of the nut, and the both screws In the ball screw composed of a plurality of balls inserted so as to be able to circulate by rolling between the grooves, the ball return passage and the circulation passage, the nut is fan-shaped for mounting the circulation piece. the counterbore forms a notch formed by cutting the open end of the ball return path facing the cutout portion so as to form at both ends, wherein the circulation piece, provided in an opening end of the circulation passage, concentric to the pocket hole Bound rotates as a fulcrum, characterized in that the formation of the annular projection for positioning the scooping path from the screw groove of the nut opposite the open end of the circulation passage.

According to the ball screw of the present invention, the connection portion from the circulation passage of the circulation piece to the ball return passage of the nut is a concentric coupling portion of the cylinder case, so that adjustment when the circulation piece is attached is performed. Can be omitted.

Further, with the rotation fulcrum of the connection adjustment scooping portion of the concentric coupling portion from the screw groove of the other of the nut to the circulation passage of the circulation piece, much easily than the assembly adjustment to the conventional In addition, a significant reduction in assembly time can be achieved.

  Accordingly, the circulation of the ball becomes smooth, and effects such as vibration suppression and noise reduction can be obtained. Further, if the spacer is sandwiched and fixed between the circulation piece and the nut, the phase difference between the ball return passage and the screw groove can be adjusted. At the same time, if a damping material is used as the spacer, vibration and sound generated between the ball and the circulation piece can be suppressed.

  The present invention will be described in detail based on the embodiments shown in the drawings.

  As shown in the perspective view of FIG. 1, a nut 20 is screwed onto the outer periphery of the screw shaft 10 indicated by a chain line. A screw groove 11 having a predetermined lead is formed on the screw shaft 10, and a screw groove 21 corresponding to the screw groove 11 is formed on the nut 20. A flange 22 is provided at the outer central portion of the nut 20, and a circulation piece 30 is fitted in each of the notches 23, 23 formed on both side surfaces.

  As shown in FIG. 2, a ball return passage 24 is provided in the nut 20, and substantially fan-shaped notches 23, 23 are formed on both ends of the return passage 24. In the nut 20 that connects the bottom portions of the 23, holes are formed in the form of through holes. Counterbores 25 and 25 are formed concentrically at both opening ends of the return passage 24.

  In this ball circulation system, a circulation piece 30 is attached to the notches 23, 23, and the ball picked up from the screw grooves 11, 21 between the screw shaft 10 and the nut 20 is transferred to the return passage 24. This is a so-called end deflector system in which a working passage is formed.

  As shown in FIGS. 1 and 3, the circulation piece 30 is shaped to fit into the fan-shaped notches 23 and 23, and the circulation piece 30 is divided into a half 30a and a half 30b as shown in FIG. Curved grooves 31 and 32 through which the ball passes are formed on each of the joint surfaces, and when these curved grooves 31 and 32 are combined, a circulation passage 33 of the circulation piece 30 is formed. The scooping groove 26 from the screw groove 21 and the return passage 24 are communicated with each other.

  Semicircular projections 34 and 35 that are annular projections at the entrance and exit of the circulation passage 33 when the half portion 30a and the half portion 30b are joined are formed at the connection portion of the circulation piece 30 to the return passage 24. ing. Further, through-holes 36 and 37 are formed in the half portions 30a and 30b, respectively, so that the half portions 30a and 30b are screwed into screw holes 27 and 27 provided in the bottom surface of the notch portion 23 of the nut 20. It has become.

  When such a circulation piece 30 is attached to the nut 20, accurate positioning can be performed by attaching the halves 30 a and 30 b one by one to the notch 23. For example, in FIG. 5, the half portion 30 a is disposed in the notch portion 23 of the nut 20 with the semi-annular protrusion 34 inserted into the counterbore 25 on the left side of the nut 20. In this state, the ball rolling surface of the curved groove 31 constituting the circulation passage 33 of the half portion 30a is made to coincide with the scooping groove 26 from the screw groove 21 of the nut 20, and the ball from the screw groove 21 to the ball So that the semi-annular protrusion 34 can be rotated as a rotation fulcrum. And it fixes with the screw 40a in the adjusted position.

  Next, the half part 30a which fixed the half part 30b first is aligned with the joint surface, and a semi-annular protrusion 35 (not shown) is inserted and disposed in the counterbore 25. And if it fixes to the nut 20 with the screw 40b, mounting | wearing of the circulation piece 30 will be completed.

  Conventionally, the smooth connection adjustment from the nut screw groove to the scooping groove could not be performed, but according to the present embodiment, fine adjustment by visual observation is possible and the efficiency of the assembly work can be achieved.

  Further, the shape of the circulation piece 30 may be a single structure. In the embodiment, the circulation piece 30 is divided into two halves 30a and 30b. However, if it is made of metal, it is made by a precision casting method such as lost wax, or if plastic is made by injection molding or the like. Even if it is integrated, the adjustment of the alignment of the scooping-up portion can be adjusted by using the annular protrusion fitted in the counterbore 25 of the return passage 24 as a rotation fulcrum.

  In addition, a spacer 50 made of a plate-shaped so-called damping material having vibration absorbing performance as shown in FIG. 6 is sandwiched between the circulation piece 30 and the nut 20, and a hole provided in the spacer 50 is passed through. The circular protrusion of the circulation piece 30 is configured to fit into the counterbore 25 of the return passage 24 and is fixed to the nut 20 after adjustment, whereby the ball passing through the circulation piece 30 and the circulation piece 30 The spacer 50 can suppress vibration and sound generated between the two.

  The spacer 50 is provided with holes through which the screws 40a and 40b are inserted. The thickness of the spacer 50 is sufficiently smaller than the height of the annular protrusion of the circulation piece 30 so as not to hinder the rotation fulcrum action of the annular protrusion. As the damping material used for the spacer 50, for example, a material such as a damping alloy manufactured by Seishin Co., Ltd. is commercially available.

Thus, the connection portion from the circulation passage 33 to return passage 24 of the nut 20 by aligning the previously not a concentric, it is possible to adjust the phase difference between the return passage 24 and the thread groove 21 of the nut 20 The adjustment when the circulation piece 30 is attached can be omitted, and the assembly time can be greatly shortened.

  In addition, about the shape of the circulation piece 30, it can employ | adopt to a both-ends rounding-up system. Even in a type in which both ends of the screw are rounded up on the screw shaft of the ball screw, the circulation piece 30 is divided into two as in this embodiment, so that only one of the circulation pieces 30 is mounted and adjusted at the stage. Can be incorporated.

  Although the half-divided circulation piece 30 has been described, it can also be implemented in an integrated shape. In this case, for example, a metal powder that enables direct modeling of metal parts from three-dimensional CAD data can be manufactured by a method such as the additive manufacturing method using laser sintering (trade name EOSINT) or a precision casting method using lost wax. it can.

1 is a perspective view of a ball screw according to Embodiment 1. FIG. It is the longitudinal cross-sectional view which notched some nuts. It is AA sectional drawing of FIG. It is an exploded assembly explanatory drawing of the circulation piece. It is a perspective view of the state which attaches the circulation piece to a nut. It is a perspective view in the state where a spacer is attached.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Screw shaft 11, 21 Thread groove 20 Nut 23 Notch part 24 Return passage 25 Counterbore 30 Circulation piece 30a, 30b Half part 31, 32 Curved groove 33 Circulation path 34, 35 Semi-annular protrusion 36, 37 Projection 40 Screw 50 spacer

Claims (5)

A screw shaft having a thread groove formed on an outer peripheral surface; a nut having a ball return passage formed in the inner peripheral surface and threaded into the screw groove in the axial direction; and between the both screw grooves. A ball circulation piece that has a curved ball circulation passage communicating with the ball return passage and is mounted on both side surfaces of the nut, and between the screw grooves, the ball return passage, and the circulation passage are rolled. In the ball screw composed of a large number of balls inserted so as to circulate, the nut is formed with fan-shaped notches at both ends for mounting the circulation piece, and the notches the counter bore is formed in the open end of the ball return path facing, wherein the circulation piece, the provided open end of the circulation passage, and rotates as a fulcrum attached concentrically to the counterbore hole The other side of the circulation passage Ball screw, characterized in that the mouth end to form an annular protrusion for positioning the scooping path from the screw groove of the nut. The circulation piece is composed of two split members each having a semi-circular projection, said circulation passage is formed by combining these joint surfaces to form the annular protrusion by combining the semi-annular protrusion together that The ball screw according to claim 1. Wherein the circulation piece after alignment to said scooping channel, a ball screw according to claim 1 or 2, characterized in that fixed to the nut.   The ball screw according to any one of claims 1 to 3, wherein a spacer is sandwiched between the circulation piece and the notch. The ball screw according to claim 4 , wherein the spacer is made of a vibration damping material.

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